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Leptospirosis is a bacterial disease that affects humans and animal, but according to Harkin, is rarely seen in cats. The bacteria are spread through the urine of infected animals, which can get into water or soil and can survive there for weeks to months. Infected wild and domestic animals may continue to excrete the bacteria into the environment continuously or every once in a while for a few months up to several years, according to the Centers for Disease Control and Prevention (CDC).

Leptospira varieties have what are termed maintenance hosts and incidental hosts. Maintenance hosts are those animal species which serve as a reservoir for the Leptospira organism, and in which transmission is very efficient. Incidental hosts include those species of animals that do not act as reservoirs, but that can be infected by the organism. The organism replicates in the kidneys of maintenance hosts and is shed in the urine. Transmission can occur to the new host, either maintenance or incidental, by coming in contact with contaminated water, soil or the carcass of an infected animal.

The disease is caused by Leptospirosis spp., a spirochete bacteria related to the bacteria that causes Lyme disease and syphilis. There are more than 300 pathogenic varieties (serovars), worldwide. Historically, in the United States, two varieties -- canicola and icterohaemorrhagiae -- were primarily responsible for the disease in dogs.

The incidence of infection from these two has declined over the past 30 years, most likely due in large measure to vaccination. The increase in cases most recently has been due primarily to the varieties pomona and grippotyphosa. Until recently no vaccine for these varieties was available.

Because of increased building and development into areas that were previously rural, pets may be exposed to more wildlife, such as raccoons, skunks, squirrels, opossums, or deer that are infected with leptospirosis.

"While people may think of Lepto as a disease spread by wildlife, it can come from backyard wildlife, including raccoons -- even city dogs can get lepto," Harkin said.

Humans are also at risk for contracting leptospirosis. Symptoms can be relatively mild and include flu-like symptoms, ocular pain, redness of the eyes, nasal discharge, fever, or muscle and joint pain; however, it can progress to more severe kidney and liver failure.

"Leptospirosis is a zoonotic disease, Harkin said. "You can get it from your pet. The bacteria can enter the body through skin or eyes, nose, or mouth, especially if the skin is broken from a cut or scratch. Drinking contaminated water can also cause infection." Harkin likens contracting the disease to being "hit by a truck."

Leptospirosis can cause an array of clinical signs. The severity of the disease can vary widely; however, leptospirosis has the potential to be severe and even fatal. Symptoms of Leptospiroris are elevated body temperature, vomiting, muscular stiffness, weakness, and inflammation of the kidney. In severe cases, jaundice and death may occur. Central nervous system signs may occur with or without other clinical signs, and organisms may be present in the brain tissue for extended periods. Chronic leptospirosis is primarily associated with chronic kidney degeneration. Shedding of leptospires in the urine may continue for over a year.

Sometimes pets do not have any symptoms. Common clinical signs reported in dogs include fever, vomiting, abdominal pain, diarrhea, refusal to eat, severe weakness and depression, stiffness, severe muscle pain, or inability to have puppies. Generally younger animals are more seriously affected than older animals. Harkin said the vast majority of dogs have a sudden onset of vomiting, which may be proceeded by muscle or joint pain or stiffness. Pet owners may mistake this early stage as arthritis and treat the dog with aspirin or another nonsteroidal anti-inflammatory drug.

A less frequent symptom seen in dogs is excessive thirst and urination. Harkin said pet owners are at risk because the dog drinks and urinates so much that they may do so in the house, exposing the owner to the disease.

If caught early, Harkin said treatment is usually effective and the survival rate is good. However, time is of the essence.

"If you let it go for three or five days, treat it with the wrong antibiotic or with inappropriate fluid therapy, it can create irreversible renal failure," Harkin said.